Actuator for a rotary valve

ABSTRACT

A hermetically-sealed actuator for a rotary valve is provided in which a valve operator is operative to move a stem axially, axial movement of the stem, in turn, producing rotation of a rotary cam member that is operatively connected to rotate a valve spindle, the axially movable stem being hermetically sealed by a bellows mechanism, thus hermetically isolating the rotary cam member from the valve operator, the maximum angular extent of rotation of the cam member being determined by the ramp cam angle and angular extent of helical slots formed in the rotary cam member and which are engaged by trunnions fast with the stem.

This application is a continuation in part of U.S. Ser. No. 794,564filed Nov. 19, 1991, now U.S. Pat. No. 5,165,657, entitled Actuator fora Rotary Valve.

FIELD OF THE INVENTION

This invention relates to an actuator for a rotary valve, and inparticular to an actuator that is totally hermetically sealed, thus toprovide a hermetically sealed rotary valve of particular use in the flowcontrol of poisonous or noxious liquids or gases.

BACKGROUND OF THE INVENTION

Bellows-type seals are commonly employed for sealing axially movablevalve members in axially movable plug or gate valves. Such bellows-typeseals are entirely successful in such valves, in that the bellows-typeseal is subjected to limited axial forces only, such forces being wellwithin the handling capability of the selected bellows-type seal, thoseforces acting exclusively in directions axially of the bellows-typeseal, and in the absence of bending or torsional forces applied to thebellows-type seal.

Such bellows-type seals also have been employed in the valve actuatorsof rotary-type valves, such as rotary plug valves, ball valves orbutterfly valves. An example of such a rotary valve is to be found inTremblay, U.S. Pat. No. 4,468,002, issued Aug. 28th, 1984. In theconstruction of that valve, a bearing, of necessity, must be providedbetween the rotary valve actuator and the bellows seal, in order topermit rotary movement of the valve actuator relative to therotationally fixed bellows seal, the bellows seal itself being incapableof rotary movement. In the construction of this patent, the bearing isprovided by a closed cap attached to one end of the bellows seal, thecap providing a bearing member that is interposed between the valveactuator and a valve actuating stem. The cap, upon actuation of thevalve actuator, is caused to move along an orbital path, this in turnresulting in axial bending stresses being produced in the bellows-typeseal, and, additionally, the imposition on the bellows-type seal oftorsional forces arising from the frictional engagement of the bearingcap with the respective valve actuator and valve actuating spindle.

Such bending and torsional forces are objectionable, in that theypromote fatigue failure of the bellows-type seal, which could havedisastrous consequences to persons in the vicinity of the valve.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a valve actuator for arotary valve, such as a ball valve, or plug valve, or butterfly valvewhich employs a bellows-type seal, but one in which the bellows-typeseal is totally isolated from any lateral displacement of thebellows-type seal, and also is totally isolated from any torsionalforces produced by actuation of the valve actuator.

The valve actuator of the present invention thus takes full advantage ofthe benefits of bellows-type seals, as employed in axially movable plugor gate valves, and employs those advantages in a hermetically sealedvalve actuator for a rotary valve, such as a rotary plug valve, ballvalve or butterfly valve.

In order to achieve this advantage, the valve assembly of the presentinvention employs a mechanism that converts rotary movement of the valveactuator into an axial movement of the valve stem, the axial movement ofthe valve stem then being re-converted into a rotary motion of therotary valve member of an associated rotary valve. In this manner, allof the advantages of a bellows-type seal can be provided in associationwith the axial movable valve stem, while at the same time, eliminatingthe need for rotary seals, and also, eliminating the imposition of anytorsional or bending forces on the bellows-type seal.

According to the present invention, the hermetically sealed actuator fora rotary valve has a main body having a bore, and an axially movablevalve actuator stem supported within said body for movement exclusivelyin a direction axially of said stem and of said bore, rotationalmovement of said stem relative to said body being precluded in itsentirety.

Adjacent one of its ends, the stem is provided with a cam follower thatcooperates with an axially fixed first rotary cam member having cammingsurfaces that cooperate with the cam follower on the stem, and which areoperative to move the stem axially in response to rotational movement ofthe cam member relative to the stem.

At an axial position remote from the cam follower, the stem carries acamming member which cooperates with an axially fixed second rotary cammember, which has camming surfaces positioned in engagement with thecamming member of the stem, those camming surfaces being operative torotate the second rotary cam member in response to axial movement of thevalve stem.

In this manner, a rotary movement of the first cam member causes acorresponding rotary movement of the second cam member, which isproduced exclusively by an axial movement of the stem.

The cam surfaces of the respective first and second camming members arenot necessarily identical with each other in ramp cam angle or inarcuate extent. In the event that they are identical with each other,then, any angle of rotation of the first rotary camming member will beduplicated in the second cam member. In the event that they aredifferent from each other, then differential rotary motion will occursuch as a 180° turn of the first camming member being operative to causea 90° turn of the second camming member.

Having reduced movements of the stem exclusively to axial movements, abellows seal can then be employed between the valve stem and the mainbody, the bellows seal being subjected exclusively to compressional andtensile loads to the total exclusion of bending and torsional loads.

In a preferred embodiment, the camming members on the stem are providedby trunnions carried by the stem, and which at their outer ends areengaged in axially directed slots formed in the main body. The firstcamming member is journalled within the main body for rotationalmovement relative thereto under the influence of camming rollers carriedby the respective trunnions. Similarly, the second cam member isjournalled within the body for rotation relative thereto under thecontrol of camming members in the form of trunnions carried by the stem.

DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described withreference to the accompanying drawings, in which:

FIG. 1 is a front elevation of a valve actuator according to the presentinvention;

FIG. 2 is a cross-section taken on the line 2--2 of FIG. 1.

FIG. 3 is a cross-section taken on the line 3--3 of FIG. 2;

FIG. 4 is a view corresponding with FIG. 2, but showing the valveactuator in an opposite position of actuation;

FIG. 5 is a cross-section taken on the line 5--5 of FIG. 4 and showingthe respective rotary cam in elevation; and

FIG. 6 is a cross-section taken on the line 6--6 of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a valve actuator according to the present inventiongenerally at 10. As will be appreciated, the actual external appearanceof the valve actuator can be varied in any desired manner to make itshorter or longer, rectangular, hexagonal, etc. However, in view of theinternal structure of the valve actuator, a cylindrical form of theactuator in all probability will be found to be the most viable.

The actuator 10 includes a main body portion 12 having an upper portion14 which is attached to the main body portion 12 by means of bolts 16.At its lower end, the main body 12 is provided with a flanged connector18, whereby the valve actuator can be secured to the body of aconventional rotary valve 20 by means of bolts 22. The rotary valve 20can be of any known type, including a rotary plug valve, a rotary ballvalve, or a rotary butterfly valve, each of which includes a rotaryvalve member that cooperates with a valve seat, as is well known in theart.

An upper portion of a rotary valve member is indicated at 24 in FIG. 2,the valve member 24 being attached to or integral with a cylindricaldrive shaft 26 that terminates at its upper end in a squared key 28.

The actuating mechanism of the valve actuator is illustrated in FIG. 2,and comprises five major elements, those elements being a first cammingmember 30, an axially movable and rotationally fixed stem 32, a secondrotary camming member 34, and, a bellows seal 36, each contained withinthe main body portion 12 and the upper body portion 14.

The first camming member 30 is supported within the upper body portion14 for rotation relative to the upper body portion 14, the first cammingmember being held against axial movement relative to the upper bodyportion 14 by C-clips 38. At its upper end, the first camming member 30is provided with some form of drive means, the drive means illustratedbeing a manually actuable handle 38 which is bolted to an upper surfaceof the first cam member 30. As will be appreciated, the handle 38equally well could be replaced by a pneumatic, hydraulic or electricdrive motor operating through an appropriate drive transmission.

The upper portion 14, as previously stated, is bolted at 16 to the mainbody portion 12. The upper body portion 14 thus rigidly attached to themain body portion 12 and is held immovable relative to the main bodyportion 12 both in axial and rotational directions. The upper bodyportion 14, at its lower end, terminates in an annular guide portion 40having a central bore within which the axially movable stem 30 isjournalled for axial movement. At its upper end, the stem 32 has a pin42 rigidly attached thereto. The pin 42 extends laterally beyond eachside of the stem 32 to provide trunnions that extend into slots 44formed in the upper portion 14. The trunnions provided by the pin 42carry anti-friction rollers 46, the anti-friction rollers 46 beingpositioned within a helical cam slot 48 formed in the first cammingmember 30.

As is common in the industry, and in order to provide what is commonlyreferred to as a quarter-turn valve, the helical cam slots 48 each havean arcuate annular extent slightly in excess of 90°, and each are ofidentical ramp cam angle. If it is desired, for example, that a 90° turnof the valve member be produced by a 180° turn of the operating handle38, then, all that is required is an appropriate decrease in the rampcam angle of the first camming member 30 and an increase in the arcuateextent of the slots 48 to slightly in excess of 180°.

The first camming member 30 has a central bore 50 in which the stem 32is guided for axial sliding movement, this feature being preferable, butnot essential, in that the stem 32 could be of square or othercross-section, in which event the upper end of the stem would beappropriately formed for it to move freely within the bore 50. Theprovision of the central bore 50 in the camming member 30 results in thehelical cam slots 48 each being formed in an outer annular portion ofthe first camming member 30, the result being that the helical cammingslots each form ramp cams for engagement with the anti-friction rollers46. Thus, on rotation of the first camming member 30 through an angularextent of, for example, 90° by rotating the handle 38 in an appropriatedirection [counterclockwise as related to FIG. 2] the ramp cams providedby the helical cam slots 48 act to pick up the anti-friction rollers 46,and, move those rollers together with the pin 42 and the stem 32 in anaxially upwards direction, the stem 32 being guided for axial movementwithin the bore of the annular guide portion 40 of the upper bodyportion 14, at the bore 50 of the first camming member 30.

Thus, it will be seen that a simple 90° turn of the handle 38 willresult in the stem 32 being raised from its lowermost position asillustrated in FIG. 2 to its uppermost position as illustrated in FIG.4, or, in the alternative, returned from the uppermost position shown inFIG. 4 to the lowermost position illustrated in FIG. 2.

At its lower end, the stem 32 is provided with a second pin 52 thatextends transversely of the lower end of the stem 32, and which also issurrounded by anti-friction rollers 46. The second pin 52 does notextend through slots in the main body portion 12 in the manner of theupper pin 42, but instead, terminates within the main body 12. Ifdesired, axially extending grooves can be provided in the interior wallof the main body 12, in which the outermost ends of the pin 52 areguided for movement axially of the body 12.

The opposite ends of the pin 52 and their surrounding anti-frictionrollers 46 extend into helical camming slots 54, as more clearlyillustrated in FIG. 5, in the second camming member 34. The secondcamming member 34 is journalled for rotation within the main body 12,and is free of any connection with the stem 32, other than at the pointsof contact of the rollers 46 with the helical cam slots 54. The secondcamming member 34 is restrained against movement axially within the mainbody 12 by a C-clip 56, the lower end of the second camming member 34being in rotational sliding engagement with an annular closure member 58provided at the lowermost end of the body portion 12. The lowermostportion of the second camming member 34 is provided centrally with asquared opening in which the squared key 28 of the valve member 24 isreceived, thus enabling rotary movement of the second camming member 34to be transmitted directly to the shaft 26 of the rotary valve 24.

As illustrated, the annular closure member 58 can be secured to the mainbody portion by welds 59 or in any other convenient manner that providesa hermetic seal between the annular closure member 58 and the main bodyportion 12. Also as is illustrated, O-rings can be provided at strategicpoints in the assembly, further to insure the hermetic sealing of theinterior of the main body portion 12.

In operation, the helical camming slots 54 produce the reverse effect tothe camming slots 48, in that while rotation of the upper camming member30 will cause raising or lowering of the stem 32, the camming slots 54will produce rotation of the second camming member 34 in the presence ofaxial movement of the stem 32. Thus, if the handle 38 is operated in adirection to open the valve, the stem 32 will be raised in an axialdirection, and, in being so raised, will cause the second camming member34 to rotate within the main body portion 12, that rotation, in turn,producing rotation of the valve member 24.

The bellows 36 extends concentrically of the stem 32, and, at its lowerend is hermetically sealed, for example, by welding, to a lower portionof the stem 32. At its upper end, the bellows 36 is hermetically sealedto the annular guide portion 40, for example, by brazing of the outersurface of the bellows to the wall of the through bore in the annularguide portion 40.

In operation of the valve actuator, in the event that any noxious fluidor gas seeps axially of the shaft 26, any such seepage then becomestrapped within the main body portion 12, and, remains trapped within themain body portion 12, the interior of the main body portion 12 beinghermetically sealed by the bellows 36.

Rotary movement of the stem 32 is precluded by the engagement of theouter ends of the pins 42 in the slots 44 of the upper body portion 14,the upper body portion 14 being non-rotatively held relative to the mainbody portion 12 by the bolts 16. Thus, despite substantial torsionalforces that can act on the stem 32, the stem 32 is immobilized againstrotation, this, in turn, relieving the bellows 36 of any bending andtorsional forces, such as could cause accelerated deterioration of thebellows 36.

While the stem 32 has been illustrated in the drawings as being axiallyof substantial length, that length and the total height of the valveactuator could be very considerably shortened by moving the annularguide portion axially towards the camming member 34, and, byappropriately shortening the main body 12 and the bellows 36, to resultin an even more compact valve actuator, as may be desirable in the eventthat the valve actuator is power-driven instead of being manuallyactuated in the manner described above.

A common requirement in the industry is for a valve that is moved 90°between its fully open and fully closed positions, those valves actingas straight-through flow valves. For certain specialized applications,such as in three-way rotary valves or multiple-way rotary valves, therequirement can arise that the valve be selectively rotated, forexample, in increments of 90° up to a total of 360°. Also, occasionsarise when a 90° turn of the valve is Produced, for example, by a 180°turn of the operating handle.

The camming member 34 provides for such differential movements of thevalve member and the valve operator, any desired rotational movement ofthe valve 34 being producible by a specific axial movement of the stem32, by suitable choice of the ramp cam angle and arcuate extent of thehelical camming slots 54 in the camming member 34. Also, differentialrotational movements of the valve 20 relative to the actuating handle 38can be provided by suitable choice of the ramp cam angle and arcuateextent of the helical camming slots 48 in the upper camming member 30,and by suitable choice of the ramp angle and arcuate extent of thehelical camming slots 54 in the camming member 34. The ramp angle andarcuate extent of the respective camming members can, for example, bearranged such that a 180° turn of the operating handle 38 results in a90° turn of the valve 24, or, for example, a 90° turn of the operatinghandle 38 results in a 45° degree turn of the valve 24, or, a turn ofany desired angular extent of the valve 24.

What is claimed is:
 1. A hermetically sealed actuator for a rotaryvalve, comprising:a main actuator body having a bore adapted to besecured to a valve housing for said rotary valve; an axially movablestem journalled and enclosed within said body for movement exclusivelyin a direction axially of said stem and said bore, said stem having acam follower; an axially fixed first rotary cam member cooperating withsaid cam follower on said stem, and operative to move said stem axiallyin response to rotational movement of said cam member relative to saidstem; a camming member carried by said stem at a position remote fromsaid cam follower; an axially fixed second rotary cam means having camsurfaces in engagement with said camming member, said second rotary cammeans being rotatable in response to axial movement of said valve stem;and, a bellows-type seal surrounding and extending along said stem andextending axially between said stem and said main body, said sealhermetically isolating said, first rotary cam member from said secondrotary cam member and extending therebetween, said first rotary cammember having helical camming slots therein, in which said cam followerof said stem is received, and said second rotary cam member havinghelical camming slots therein in which said camming member of said stemis received, said helical camming slots of said first rotary cam memberbeing of a ramp cam angle and arcuate extent different from that of saidhelical camming slots of said second rotary cam member, whereby saidrotation of said first rotary cam member by a determined angular extentproduced rotation of said second rotary cam member by a differentangular extent.
 2. The valve actuator of claim 1, in which said firstrotary cam member is connected to a drive means for rotating said firstrotary cam member.
 3. The valve actuator of claim 2, in which said drivemeans is a manually actuable handle.
 4. The valve actuator of claim 1,in which said first rotary cam member is journalled in said main bodyfor rotational movement within said main body to the exclusion of axialmovement.
 5. The valve actuator of claim 1, in which said second rotarycam member is journalled in said main body for rotational movementwithin said main body to the exclusion of axial movement relative tosaid main body.
 6. The valve actuator of claim 1, including means forattaching said main body to a rotary valve with said second rotary cammember in rotary driving connection with a rotary valve spindle of saidvalve.
 7. The valve actuator of claim 1, in which said cam follower andsaid camming member of said stem each are provided by trunnions fastwith said stem and extending perpendicular to the longitudinal axis ofsaid stem.
 8. A hermetically sealed actuator for rotary valve,comprising:a main actuator body having a bore adapted to be secured to avalve housing for said rotary valve; an axially movable stem journalledand enclosed within said body for movement exclusively in a directionaxially of said stem and said bore and to the exclusion of rotarymovement of said stem relative to said body; operating means operativeto move said stem axially in response to operation of said means; acamming member carried by said stem at a position remote from saidoperating means at one end is said body; an axially fixed rotary cammember having helical cam surfaces in engagement with said cammingmember and positioned at the other end of said body, said rotary cammember being rotatable in response to axial movement of said valve stem;and, a bellows-type seal surrounding and extending along said stem andextending axially between said stem and said main body, said sealhermetically isolating said rotary cam member from said operating meansand extending therebetween, said helical cam surfaces of said rotary cammember being of determined ramp cam angle and arcuate extent, whereby adetermined axial movement of said stem will produce a determined angleof rotation of said camming member.
 9. The valve actuator of claim 8, inwhich said rotary cam member is journalled in said main body forrotational movement within said main body to the exclusion of axialmovement.
 10. The valve actuator of claim 8, including means forattaching said main body to a rotary valve with said rotary cam memberin rotary driving connection with a rotary valve spindle of said valve.11. The valve actuator of claim 8, in which said camming member of saidstem is provided by trunnions fast with said stem and extendingperpendicular to the longitudinal axis of said stem.
 12. A hermeticallysealed actuator for a rotary valve, comprising:a main actuator bodyhaving a bore adapted to be secured to a valve housing for said rotaryvalve; an axially movable stem journaled and enclosed within said bodyfor movement exclusively in a direction axially of said stem and saidbore, said stem having a cam follower; an axially fixed first rotary cammember cooperating with said cam follower on said stem, and beingoperative to move said stem axially in response to rotational movementof said cam member relative to said stem, said first rotary cam memberbeing journalled in said body exclusively for rotary movement withinsaid body; a camming member carried by said stem at a position remotefrom said cam follower; an axially fixed second rotary cam means havingcam surfaces in engagement with said camming member, said second rotarycam means being rotatable in response to axial movement of said valvestem, said second rotary cam member being journalled in said bodyexclusively for rotary movement within said body; and, a bellows-typeseal surrounding and extending along said stem and extending axiallybetween said stem and said main body, said seal hermetically isolatingsaid first rotary cam member from said second rotary cam member andextending therebetween, said first rotary cam member having helicalcamming slots therein, in which said cam follower of said stem isreceived, and said second rotary cam member having helical camming slotstherein in which said camming member of said stem is received, saidhelical camming slots of said first rotary cam member being of a rampcam angle and arcuate extent different from that of said helical cammingslots of said second rotary cam member, whereby said rotation of saidfirst rotary cam member by a determined angular extent produced rotationof said second rotary cam member by a different angular extent.
 13. Thevalve actuator of claim 12, in which said first rotary cam member isconnected to a drive means for rotating said first rotary cam member.14. The valve actuator of claim 13, in which said drive means is amanually actuable handle.
 15. The valve actuator of claim 12, includingmeans for attaching said main body to a rotary valve with said secondrotary cam member in rotary driving connection with a rotary valvespindle of said valve.
 16. The valve actuator of claim 12, in which saidcam follower and said camming member of said stem each are provided bytrunnions fast with said stem and extending perpendicular to thelongitudinal axis of said stem.
 17. A hermetically sealed actuator for arotary valve, comprising:a main actuator body having a bore adapted tobe secured to a valve housing for said rotary valve; an axially movablestem journalled, within said body for movement exclusively in adirection axially of said stem and said bore and to the exclusion ofrotary movement of said stem relative to said body; operating meansoperative to move said stem axially in response to operation of saidmeans; a camming member carried by said stem at a position remote fromsaid operating means at one end of said body; an axially fixed rotarycam member journalled in said body exclusively for rotary movementwithin said body and positioned at the other end of said body, saidaxially fixed rotary cam member having helical cam surfaces inengagement with said camming member, said rotary cam member beingrotatable in response to axial movement of said valve stem; and, abellows-type seal surrounding and extending along said stem andextending axially between said stem and said main body, said sealhermetically isolating said rotary cam member from said operating meansand extending therebetween, said helical cam surfaces of said rotary cammember being of determined ramp cam angle and arcuate extent, whereby adetermined axial movement of said stem will produce a determined angleof rotation of said camming member.
 18. The valve actuator of claim 17,including means for attaching said main body to a rotary valve with saidrotary cam member in rotary driving connection with a rotary valvespindle of said valve.
 19. The valve actuator of claim 17, in which saidcamming member of said stem is provided by trunnions fast with said stemand extending perpendicular to the longitudinal axis of said stem.